Upholstery Sewing Threads and Sewing 102570 GB00PDF029 Upholstery

Service & Technology Information for the sewing industry

Upholstery Sewing Threads and Sewing 102570 GB00PDF029 Upholstery – Sewing Threads and Sewing

Upholstery Sewing upholstery Seam quality standards for upholstered furniture are very high. Sewing thread When developing these products, seam and production planning Primarily polyester or polyamide sewing threads are used for sewing must consider the visual and functional aspects. upholstery. Both are common in practice. The size must correspond to the material and must be synchronised to the seam stability required. This can vary depending on the material, sewing operation, and purpose. All sewing thread construction types are used. In practice continuous filaments are often preferred due to their high technical performance. This construction type is typical, especially for sewing leather. AMANN recommends the following sewing threads for the sewing operation listed below: Closing seams (incl. piping seams): SabaC, polyester/polyester corespun 25, 35, 50 Rasant, polyester/cotton corespun 25, 301), 35, 50 Saba, polyester cut staple 30 Serafil, polyester continuous filament 30, 40 ONYX, polyamide continuous filament 30, 40 On the one hand seams are a decorative element, shaping design Piping seams are sometimes pre-sewn with a finer thread size. The and overall appearance. But they have to be tough to endure the actual closing piping seam is sewn thereafter with the same thread assembly. They are also influential in performance-related design for size as the closing seams to reach the required strong seam lock and the level of quality of the furniture. For perfect seams, even when to prevent diverging seams under crosswise strain. exposed to high stresses in later use, seam stability, seam abrasion resistance, and seam elasticity are of utmost importance. Most of Overedging the seams are exposed to high tension stress in a lengthwise and SabaC, polyester/polyester corespun 120, 150 crosswise direction during final assembly and on the finished piece. Rasant, polyester/cotton corespun 120 If seam stability and seam elasticity are insufficient due to unsuitable PaxX, polyester continuous filament, sewing parameters, broken seams will be the result. Seam abrasion air-jet, texturised 150 resistance is also decisive for the product's quality in later use. All Serafil, polyester continuous filament 120/2 visible seams are not to show signs of wear and tear, even after SabaTEX, polyester continuous filament, long-term use. This isn’t easy if you keep in mind the characteristic texturised 100, 120 abrasion stress on seating furniture. Decorative seams A real challenge facing upholstery production is the great variety in SabaC, polyester/polyester corespun 25, 35 different materials. Woven fabrics, knitted fabrics, leather (artificial 1) and genuine), thick- or thin-coated or covered – anything’s possible, Rasant, polyester/cotton corespun 25, 30 , 35 to some extent even in combination. The sewing parameters must Saba, polyester cut staple 8, 30 always be individually adjusted to the materials. Serafil, polyester continuous filament 10, 15, 20, 30, 40 ONYX, polyamide continuous filament 10, 13, 20, 30, 40 Upholstery repair is time consuming and very costly – one more rea- Serabraid, polyester continuous filament, son to ensure optimal seam quality, to plan the seams very carefully, braided2) 800, 1000, 1200, 1400 and to consistently implement the suitable processing parameters in production. The continuous filaments Serafil and ONYX, with their smooth surfaces, are ideally suited for genuine and artificial leather and are therefore often used for this. In addition, the abrasion resistance of continuous filaments is very high, which is extremely beneficial for a long product life.

1) Rasant 30 is a polyamide/cotton corespun 2) Serabraid is available in the qualities T90 (heavily waxed hand sewing thread) and T60 (lightly waxed machine sewing thread)

Service & Technology 2 SabaC, Rasant and Saba have a very soft and textile structure. They Needle point are preferably used for topstitching fabrics or knitted fabrics, when The kind of needle point depends on the type of material used. We a rather rustic or sportive character is intended. recommend the following needle points: Braided sewing threads like Serabraid allow very distinctive seam Woven and knitted fabrics: patterns and are often used when the seams are to be used as a Round or ball points: for example R or FFG/SES special design feature. Upholstery without decorative seams is un- imaginable. Leather combined with woven fabrics: Round or ball points: for example R or FFG/SES Needles Leather: Needle size Round or cutting point with small triangular cutting edge: for example R, SD1 or SD Nm 90 - 140 SIZE 14 - 22 In practice other cutting points are also used for decorative seams on leather. The needle size depends on the material and the number of plies. Usually, the needle sizes Nm 90-140 (Size 14-22) are used. For A cutting point’s grind is decisive for a stitch’s position in the seam and thicker decorative seams it may be necessary to use a thicker needle thus for its appearance. Different cutting points, for example in lens, size. Especially for braided threads, needles of size Nm 190 and diamond, or triangle shape, allow many more seam variations. You thicker must be used to ensure an optimal guidance of the sewing may choose from various cutting points depending on the look you thread through the fabric. want, for example: For more information on which needle to use, see the special sewing recommendations at the end of this chapter.

Cutting point needles © Groz-Beckert KG Cutting point needles © Groz-Beckert KG

3 Stitch type Special sewing recommendations Lockstitches (stitch type 301) are mainly used for upholstery closing Diverging seams and topstitching seams as for piping seams. To prevent stitches from gaping, it is extremely important to maintain Overlock stitches (stitch types 502, 503, 504 or 505) are used for the correct thread tension and thread balance between needle and overedging woven and knitted fabrics. bobbin thread. Upholstery covers on the finished sofa or armchair The double chainstitch (stitch type 401) is used where additional width are usually under stress, and "open" seams are very obvious and needs to be worked in or for pre-sewing round corners. affect product quality. Machines Seam elasticity Decorative seams often have low stitch density for fashionable rea- Lockstitch machines (joining and decorative seams); sons, and therefore they often have low seam elasticity. To protect Double chainstitch machines for pre-sewing; these seams from overstretching (breaking) when the covers are Overlock machines (overedging) stretched, it may be necessary to apply seam tape which limits seam The sewing machines must be equipped for medium or heavy mate- elasticity. rials when processing upholstery. For the often very large fabric Needles for special applications parts, long-arm machines are required for the topstitching. Com- mon machines used in practice are those with combined bottom, For 2-needle-topstitching used on upholstery covers for sewing in needle, or top feed machines, or with an intermittent puller feed. zippers and for decorative seams or for stitching holding seams on These ensure perfect feed even for cross-seams, a high number of both inside and outside, the use of a needle with right-twisted point layers or thick material. A smooth and even material feed is difficult grove (CR needle) for the left needle is beneficial. with machines equipped only with bottom feeds. Feed pucker is also Thus, the unravelling effect of the sewing thread in the left needle a risk. To avoid this problem, the machine operator will have to assist can be reduced. Especially when using thicker sewing threads, the by guiding the material manually. left needle thread tends to show twist displacement that is unfavo- Machines with an adjustable presser foot pressure are very helpful urable for the appearance of the seam, and can lead to sewing for sewing materials of varying thicknesses. process disturbances when the looper thread is inserted into the Often machines for upholstery production feature an air needle open needle thread loop instead of the whole needle thread. The cooling system to prevent the needle from overheating and resulting twisted point groove protects the needle thread better and prevents disturbances. this problem. For sewing thicker decorative seams, one needs machines that are suited for handling thicker sewing threads. For this, a thicker sewing set is necessary; with a big enough stitch hole for the thicker needles and a big opening for the hook. The stitch length must also be variable, also for long stitch lengths. Stitch density For joining seams, the stitch density should be approx. 3 stitches/cm. The stitch density not only determines seam stability, it significantly influences seam elasticity too – an important quality indicator when stretching upholstery covers. Therefore stitch density must be individually adapted to the required seam elasticity. For elastic materials, clearly higher stitch densities of more than 3 stitches per cm may be necessary. For decorative seams, the stitch density is set to create the desired seam look. It can even be lower, for example 2 stitches/cm.

Service & Technology 4 Because this special needle is produced in few needle systems only, By the way: Dark materials like black or dark blue tend ® we recommend using the SAN 5 needle from Groz-Beckert as an to develop more sewing process disturbances and material ® alternative. The Groz-Beckert SAN 5 needle features a deep hol- ! damage than lighter colours. Practice has shown more than low profile and a special eye form with an extended eye groove once that different colours of the same material display different edge, which protects the sewing thread even better and reduces processing properties. Some darker materials therefore require twist displacement. special attention for processing. Optimal sewing parameters are Needle change required. However, if this does not achieve successful results it is up to the fabric manufacturer to improve its product for a better It is very important to change the needles regularly because of the sewability of the material. high stresses to which they are exposed to in upholstery production. This can be clearly defined as a preventive quality assurance measure. Sometimes it may be necessary to change the needle at the beginning of each new shift to avoid needle damage and related sewing process disturbances and material damage. Thread take up spring The thread take up spring, which is very important for good stitch looking, is a wearing part that should be regularly checked. If the thread take up spring is not working properly it reveals itself with suddenly occurring loose stitches. This can be balanced out to some extent with the thread tension but it exposes the sewing thread to great stress.

5 Checklist

Problem Cause Suggested solution Damaged needle point Replace needle Insufficiently polished eye Use optimal needle Burr on hook Polish or replace hook Thread breaks during Burr on stitch hole, feed dog Polish to remove burrs sewing Incorrect needle/hook adjustment Adjust needle/hook as good as possible Needle eye not in line with hook Exactly align needle with hook Needle thread melts Install needle air cooling system, reduce speed Sewing thread was mechanically damaged Remove burrs from thread guiding paths. during sewing Provide 3 or 4 backstitches at beginning and Broken seams on Beginning and end of seam not properly backtacked finished product end of seam Insufficient seam stability Maintain or increase defined stitch density/cm Wrong needle point used for stitching Use correct point form, R instead of LR Needle/under thread ratio for lockstitch is about Needle and under thread not balanced correctly 50 : 50 Bobbin case opener of sewing machine does not Irregular stitch looping Adjust bobbin case opener properly work properly Machine not suited for extremely coarse sewing Use suitable machine for coarse threads threads

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7 All recommendations presuppose adjustment of the sewing conditions to the appropriate sewing yarn. yarn. sewing appropriate the to conditions sewing the of adjustment presuppose recommendations All All facts and figures are intended exclusively for your information. Phone 7 Hauptstrasse 1 AMANN & Soehne GmbH & Co. KG Fax n a member of member a t 4357 Boennigheim - Germany @

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102570 All data were arranged after best knowledge and certain and correspond to the conditions during printing. GB00PDF029 For mistakes, misprint and any changes of the instructions no adhesion. All illustrations are noncommittal.